1. Field of the Invention
This invention relates to a method for removing engine deposits in a gasoline internal combustion engine. More particularly, this invention relates to a method for removing engine deposits in a gasoline internal combustion engine which comprises introducing a cleaning composition into an air-intake manifold of the engine and running the engine while the cleaning composition is being introduced.
2. Description of the Related Art
It is well known that automobile engines tend to form deposits on the surface of engine components, such as carburetor ports, throttle bodies, fuel injectors, intake ports and intake valves, due to the oxidation and polymerization of hydrocarbon fuel. These deposits, even when present in relatively minor amounts, often cause noticeable driveability problems, such as stalling and poor acceleration. Moreover, engine deposits can significantly increase an automobile""s fuel consumption and production of exhaust pollutants.
Recently, direct injection spark ignition (DISI) engines have been introduced as an alternative to conventional port fuel injection spark ignition (PFI SI) engines. In the past few years, at least three types of DISI engines (from Mitsubishi, Toyota, and Nissan) have been commercially introduced into the Japanese market, and some models are now available in Europe and selected markets in Asia. Interest in these engines stems from benefits in the area of fuel efficiency and exhaust emissions. The direct injection strategy for spark ignition engines has allowed manufacturers to significantly decrease engine fuel consumption, while at the same time maintaining engine performance characteristics and levels of gaseous emissions. The fuel/air mixture in such engines is often lean and stratified (as opposed to stoichiometric and homogeneous in convention PFI SI engines), thus resulting in improved fuel economy.
Although there are many differences between the two engine technologies, the fundamental difference remains fuel induction strategy. In a traditional PFI SI engine, fuel is injected inside the intake ports, coming in direct contact with the intake valves, while in DISI engines fuel is directly introduced inside the combustion chamber. Recent studies have shown that DISI engines are prone to deposit build-up and in some cases, these deposits are hard to remove using conventional deposit control fuel additives. Given that the DISI engine technology is relatively new, there is concern that with accumulated use, performance and fuel economy benefits may diminish as deposits form on various surfaces of these engines. Therefore, the development of effective fuel detergents or xe2x80x9cdeposit controlxe2x80x9d additives to prevent or reduce such deposits in DISI engines is of considerable importance.
Generally, detergents and other additive packages have been added to the fuel in gasoline engines to prevent formation of and to remove deposits which are formed by the heavy components of the fuel. Typically, for these detergent additives in the fuel to remove deposits from the various parts of an engine, they needed to come into contact with the parts that require cleaning. As a consequence, problems in fuel delivery systems, including injector deposit problems, have been significantly reduced. However, even these components require occasional cleaning. Specific engine configurations have more pronounced problematic deposit areas due to the intake systems. For example, throttle body style fuel injector systems where the fuel is sprayed at the initial point of air flow into the system allows the intake to remain reasonably clean using the fuel additive, however PFI SI engines spray the fuel directly into the air stream just before the intake valves and DISI engines spray the fuel directly into the combustion chamber. As a result, upstream components from the fuel entry on the intake manifold of PFI SI and DISI engines are subject to increased formation of unwanted deposits from oil from the positive crankcase ventilation (PCV) system and exhaust gas recirculation (EGR). These upstream engine air flow components can remain with engine deposits even though a detergent is used in the fuel. Even with the use of detergents, some engine components when present, such as intake valves, fuel injector nozzles, idle air bypass valves, throttle plates, EGR valves, PCV systems, combustion chambers, oxygen sensors, etc., require additional cleaning.
Several generic approaches were developed to clean these problematic areas often focusing on the fuel systems. One common method is applying a cleaning solution directly to the carburetor into an open air throttle or the intake manifold of a fuel injection system, where the cleaner is admixed with combustion air and fuel, and the combination mixture is burned during the combustion process. These carburetor-cleaning aerosol spray cleaning products are applied to soiled areas into a running engine. The relatively slow delivery rate as well as the structure of the carburetor/manifold systems generally prevent the accumulation of cleaning liquid in the intake of the engine. However as is apparent for the intake manifold, the majority of the cleaner will take the path of least resistance to the closest combustion chamber of the engine often leading to poor distribution and minimal cleaning of some cylinders.
This technique has also been modified, to introduce a cleaning solution to the intake manifold through a vacuum fitting. Generally, these cleaning solutions are provided in non-aerosol form, introduced into a running engine in liquid form using engine vacuum to draw the product into the engine, as described in U.S. Pat. No. 5,858,942 issued Jan. 12, 1999. While these newer products may be generally more effective at cleaning the engine than the conventional aerosol cleaners, they suffer from a distribution problem in getting the cleaner to the multiple intake runners, intake ports, intake valves, combustion chambers, etc. Generally, the cleaning product was introduced into the intake manifold via a single point by disconnecting an existing vacuum line on the manifold and connecting a flex line from that vacuum point to a container containing the cleaning liquid and using engine vacuum to deliver the cleaning solution to that single port. While a metering device could be used limit the rate at which the cleaning solution was added to the intake manifold, the locations for addition of cleaning solution were fixed by the engine design of vacuum fittings on the intake manifold. Often such arrangements favored introduction of cleaning solution to some of the cylinders while others received less or none of the cleaning solution. More problematic is that some engine designs have an intake manifold floor, plenum floor or resonance chamber, which has a portion lower than the combustion chamber of the engine. This type of design will allow for cleaning solution to pool in these areas. This aspect, as well as introducing the cleaning solution at too great a rate, can accumulate and pool the cleaning solution in the manifold even though the engine is running. Generally, the vacuum generated within the manifold is not sufficient to immediately move this pooled liquid or atomize the liquid for introduction into the combustion chamber. However, upon subsequent operation of the engine or at higher engine speed, a slug of this liquid can be introduced into the combustion chamber. If sufficient liquid is introduced into the combustion chamber, hydraulic locking and/or catastrophic engine failure can result. Hydraulic locking and engine damage can result when a piston of the running engine approaches its fully extended position towards the engine head and is blocked by essentially an incompressible liquid. Engine operation ceases and engine internal damage often results.
Accordingly, disclosed herein is a method for removing engine deposits in a gasoline internal combustion engine and an illustrative apparatus for introducing a cleaner composition into an operating gasoline internal combustion engine, while providing discrete variable locations within an intake vacuum system for introduction of the cleaning solution. Such discrete locations can be independent of the engine vacuum port configuration and can be used to reduce or eliminate the possibility of pooling the cleaner solution into the intake manifold while allowing for improved distribution of the cleaner solution to affected areas.
The present invention provides a method for removing engine deposits in a gasoline internal combustion engine which comprises introducing a cleaning composition into an air-intake manifold of a warmed-up and idling gasoline internal combustion engine and running the engine while the cleaning composition is being introduced, said cleaning composition comprising:
(a) a phenoxy mono- or poly(oxyalkylene) alcohol having the formula: 
wherein R and R1 are independently hydrogen or methyl and each R is independently selected in each xe2x80x94CH2xe2x80x94CHRxe2x80x94Oxe2x80x94 unit; and x is an integer from 0 to 4; and mixtures thereof;
(b) at least one solvent selected from:
(1) an alkoxy mono- or poly(oxyalkylene) alcohol having the formula: 
wherein R2 is alkyl of 1 to about 10 carbon atoms; R3 and R4 are independently hydrogen or methyl and each R3 is independently selected in each xe2x80x94CH2xe2x80x94CHR3xe2x80x94Oxe2x80x94 unit; and y is an integer from 0 to 4; and mixtures thereof; and
(2) an aliphatic or aromatic organic solvent; and
(c) at least one nitrogen-containing detergent additive.
In a preferred embodiment, the method of the present invention further comprises the subsequent step of introducing a second cleaning composition into the air-intake manifold of the warmed-up and idling engine and running the engine while the second cleaning composition is introduced, said second cleaning composition comprising a homogeneous mixture of:
(a) a phenoxy mono- or poly(oxyalkylene) alcohol having the formula: 
wherein R and R1are independently hydrogen or methyl and each R is independently selected in each xe2x80x94CH2xe2x80x94CHRxe2x80x94Oxe2x80x94 unit; and x is an integer from 0 to 4; or mixtures thereof;
(b) an alkoxy mono- or poly(oxyalkylene) alcohol having the formula: 
wherein R2 is alkyl of 1 to about 10 carbon atoms; R3 and R4 are independently hydrogen or methyl and each R3 is independently selected in each xe2x80x94CH2xe2x80x94CHR3xe2x80x94Oxe2x80x94 unit; and y is an integer from 0 to 4; or mixtures thereof; and
(c) water.
In an alternative embodiment, the present invention is further directed to a method for delivering a cleaning composition to the intake system of a gasoline internal combustion engine which comprises introducing a cleaning composition into an air-intake manifold of a warmed-up and idling gasoline internal combustion engine through a transport means inserted into and located within the interior of the engine to thereby deliver the cleaning composition to each combustion chamber, and running the engine while the cleaning composition is being introduced. This transport means is separate from the fuel delivery system of the engine.
Among other factors, the present invention is based on the discovery that intake system deposits, particularly intake valve and combustion chamber deposits, can be effectively removed in gasoline internal combustion engines by employing the unique method described herein. Moreover, the method of the present invention is suitable for use in removing deposits in conventional engines including conventional port fuel injection spark ignition (PFI SI) engines and in direct injection spark ignition (DISI) gasoline engines. The present method is especially suitable for use in DISI gasoline engines.